Trump risks confidence in U.S. role as guardian of global shipping

Of all the things Donald Trump has done to disrupt global commerce, from levying punitive tariffs to tearing up trade deals, few would be as consequential as withdrawing and leaving the rest of the world to secure the Persian Gulf.

The move, which the US president has repeatedly threatened as his war with Iran drags on, would represent a break with decades of US policy keeping open the sea lanes that carry four-fifths of the $35 trillion global goods trade. Even the threat of reducing security for the Strait of Hormuz risks shaking confidence in a pillar of the world economy, as well as American wealth and power.

Traffic through the strait has dropped to a handful of ships daily from about 135 before the war, with Iran allowing passage mainly for its own exports. Those conditions are putting at risk roughly one-fifth of global oil flows, driving up prices and injecting volatility into energy markets.

Since World War II, the US has used its navy to deter attacks, counter piracy and challenge attempts by states to restrict lawful passage across the ...